Mental Privacy under Article 21: Constitutional Limits on Neurotechnological Data Extraction in India

The emergence of consumer and commercial neurotechnologies capable of extracting, processing, and inferring cognitive data from neural signals presents Indian constitutional privacy jurisprudence with a challenge that existing doctrine is structurally ill-equipped to address. While the nine-judge bench in Justice K.S. Puttaswamy (Retd.) v. Union of India established privacy as a fundamental right under Article 21 of the Constitution, recognizing informational privacy, decisional autonomy, and dignity as its interlocking dimensions, the framework was elaborated against a background of conventional data collection. Neurotechnological systems, including electroencephalographic wearables, affective computing interfaces, cognitive analytics platforms, and neural biometric systems, operate at a constitutively different register: they access cognitive states before their expression, generate probabilistic inferences about mental processes from physiological signals, and collapse the conventional distinction between information a person possesses and information that is constructed from her neural activity. This paper argues that neurodata occupies a constitutionally distinct category from ordinary personal data because its extraction compromises not merely informational privacy but the pre-expressive substrate of decisional autonomy itself. Critically examining the Digital Personal Data Protection Act, 2023, the paper identifies structural deficiencies in neurodata classification, inferred data governance, and consent architecture that render the statute inadequate as a governance framework. Drawing selectively on Chile’s 2021 constitutional neurorights amendment and the EU Artificial Intelligence Act’s restrictions on cognitively intrusive systems, the paper argues that the Puttaswamy framework, properly extended, can accommodate a doctrine of mental privacy within Article 21 without requiring entirely new constitutional language. A tripartite constitutional standard is proposed: cognitive integrity protection, a doctrine of inferential restraint, and heightened proportionality review for neurotechnological intrusions. This framework reflects the constitutional values of dignity, autonomy, and mental self-determination already embedded in India’s privacy jurisprudence, and is capable of governing the specific constitutional harm that neurodata extraction poses.